If a steering device of a railway vehicle steering truck is damaged by some cause or other, it is necessary to prevent the damaged structural component from dropping onto a surface of a track or to prevent it from making contact with a surface of a track.
For example, in FIG. 9 of Patent Reference 1, there is described a truck equipped with an ordinary axle box suspension arranged in parallel with a steering device. Such a truck is able to travel even if the steering device is damaged.
However, in Patent Reference 1, there is no recitation regarding preventing the damaged structural component from falling onto the surface of the track if the steering device is damaged.
In other words, if the steering device of the steering truck became damaged, it was necessary to newly install a component to prevent dropping, so as to prevent the damaged structural component from dropping onto the surface of the track, and to prevent contact with the track.